Boiler stopped working? What to check before you call

When the heating or hot water cuts out, the useful first step is working out whether it is a quick reset, a settings issue, or something that needs a Gas Safe engineer.

Check the boiler pressure

Most sealed heating systems should sit around 1 to 1.5 bar when cold. If the gauge is much lower, the boiler may lock out to protect itself. If you know how to top up your model safely, bring it back into range and reset the boiler.

If the pressure keeps dropping after you top it up, stop repeating the same fix. That usually means a leak, a failing expansion vessel, or a pressure relief issue.

Check power and controls

It sounds basic, but we see it all the time:

• The fused spur beside the boiler has been switched off.
• The programmer is still in holiday mode.
• The thermostat batteries have died.
• A smart thermostat has lost connection after a router change.

If the boiler display is completely blank, check the local switch and consumer unit before booking a repair.

Write down the fault code

Most modern boilers show an error code when they lock out. Take a photo of the display before resetting it. That code tells us where to start and can save time on the visit.

Do not ignore these signs

Call straight away if you can smell gas, see scorching around the boiler, hear unusual banging, or notice water dripping from inside the casing. If you smell gas, turn the gas off at the meter if safe to do so, open windows, leave the property, and call the National Gas Emergency Service on 0800 111 999.

When to book a repair

If the boiler keeps locking out, loses pressure again, trips the electrics, or has no hot water after the basic checks above, it needs diagnosing properly. Send the fault code, boiler make and model, postcode, and a quick description of what changed before it failed.

That gives us enough to decide whether it is likely to be a same-day repair, a part order, or a service issue.